for class can tell (non-virtual) superclasses via attribute __mro__ , (non-virtual) subclasses calling __subclasses__.
for abc can tell virtual subclasses via attribute _abc_registry.
is there way tell virtual superclasses of class, i.e. classes registered virtual subclass?
for abc can tell virtual subclasses via attribute '_abc_registry'.
no can't. can find explicitly registered virtual subclasses way. handled __subclasshook__ won't show in check.
to you're trying do, you'd have go through every abc ever defined in python session , call isinstance. while technically possible in cpython traversing type hierarchy __subclasses__ method, it's bad idea.
